Studies of the effects of added GM1 and GD1a on murine neuroblastoma cells indicate that the different gangliosides have different effects on the cells. These studies will be continued to determine the specific changes induced by the gangliosides and to study the cellular effects of other gangliosides. Ongoing studies of the ganglioside patterns of human neuroblastomas suggest that the lack of GT1b indicates a poor prognosis. Extracts of brains of newborn mice contain a factor which can inhibit neuroblastoma growth in vitro. Experiments to further characterize this factor(s) will be continued.